Studies on certain yeasts associated with animals

Nimir, Abdelhafeez Hassan (1980) Studies on certain yeasts associated with animals. PhD thesis, University of Glasgow.

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The objectives of this study were to investigate the significance of yeasts as animal disease agents in the West of Scotland, to study the commensal association of yeasts with animals and, in particular, to assess the possibility of applying serological tests in the diagnosis of feline cryptococcosis. Examination of pathological specimens from various animal sources revealed that animal diseases attributable to yeasts were not common in this area. Apart from otitis externa in dogs, with which Pityrosporum pachydermatis was associated, other disease conditions were only sporadically encountered. Candida albicans was associated with 2 cases of oral thrush in adult guinea-pigs and with 3 cases of gastrointestinal ailments in puppies. Torulopsis pintolopesii was incriminated in causing a fatal gastrointestinal and systemic infection in a racing pigeon. No previous systematic studies have been done to investigate the commensal existence of yeasts on and in dogs and cats. In this study, cultural surveys were undertaken to investigate the prevalence of yeasts in those hosts. It was established that yeasts might occur as commensals on normal canine skin and in the nasal cavities of apparently normal dogs and cats. Besides its association with canine otitis externa, Pit, pachydermatis was found in association with skin infections in dogs. The association of C . albicans with oral infection in 2 guinea-pigs prompted a cultural study to see if this and other yeasts were prevalent in the oral cavity of healthy guinea-pigs. Candida albicans and Saccharomyces telluris were found to exist as normal inhabitants in this site . The value of serological methods in the diagnosis of animal cryptococcosis has not previously been determined. A serological survey owas undertaken to test sera from apparently normal cat and dog populations for the presence of antibody to Cryptococcus neoformans. Three tests, namely, counterimmunoelectrophoresis, immunodiffusion and agglutination tests were employed. Counterimmunoelectrophoresis proved more sensitive than the other tests. Using it, precipitating cryptococcal antibody was demonstrated in a proportion of cats and dogs. The antibody response was thought to have resulted from exposure to the yeast in the environment. The use of serology in the diagnosis of feline cryptococcosis was evaluated in experimentally infected cats. The 3 tests were used to examine sera and other body fluids from experimental cats for the presence of antibody and/or antigen. It was established that the presence of serum cryptococcal antigen was proof of active cryptococcosis in the cat. On the other hand, the presence of circulating cryptococcal antibody alone could not be regarded as evidence of such disease. Its presence, however, may suggest early or past infection, or simply exposure to the organism. The role of black yeasts as disease agents in domestic animals is not known and has not previously been investigated. In this study, 3 black yeast isolates from animal sources were identified and their pathogenicity for mice determined. One isolate, a Cladosporium species, was found to be non-pathogenic. Two isolates of Fonsecaea dermatitidis were highly virulent to mice and had a marked neurotropic affinity. Although not yet determined, the possibility that this species is pathogenic to domestic animals, could not be dismissed. The literature on diseases caused by yeasts in animals is reviewed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Christine O Dawson
Keywords: Veterinary science, Animal diseases
Date of Award: 1980
Depositing User: Enlighten Team
Unique ID: glathesis:1980-72706
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06

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